Forest Disease Newsletter: Gypsy Moth in 1997

Gypsy moth in 1997: The year in review

The year in our rear view mirror was most interesting, not just here in Minnesota, but in our neighboring states as well. At first glimpse, Minnesota produced 261 moths in the pheromone trapping grid. This was not even close to the record of 580 moths taken in 1984 or the "Breach Year" (1994) catch of 350 moths. All the news is not good, in fact, the good news may be downright misleading. We have actually seen a dramatic increase in the number of sites over the past three years: from 67 in 1995, to 117 in 1996, and to 154 in 1997. The increase in just the last year was 37 new sites. In the county department, we tied the record of 25 counties established in 1995.

The most significant increase in site numbers was produced in three key southeastern counties of Fillmore, Houston, and Winona. In 1994, this area was trapped and produced just four moths at four sites. This year's take was an astounding 65 moths from 49 sites. Why the increase?

Clearly the leading edge of the infestation has moved much closer to us in the last three years.(Gypsy moth counts in the tri-state area.) Moving much faster than predicted by USDA models, the advancing front has now placed four Wisconsin and three Michigan UP counties under general quarantine and an additional six gazillion counties (see map) under provisional quarantine as of September (1997). General quarantine institutes full, normal regulations enforced by the USDA APHIS and the state Agriculture departments. Provisional quarantine defines a "transition area" where special transitional regulations are put in place.

The appearance of scattered moths at a large number of Minnesota sites is about as much a surprise as burning embers being thrown ahead of a raging forest fire. And about as subtle! Do the words "spot fire" ring a bell for you? (Map of potential gypsy moth damage in Minnesota.) Remember the little gypsy moth cards designed to raise the awareness of the traveling public, particularly the "camping crowd". With infested areas just a few hours away, it should not surprise us that we are seeing an increase in spot fires, er . . I mean moth catches. Closer to home, DNR trappers took moths at four locations this past year, a new record: three campgrounds and a wayside rest including Beltrami, Itasca, Lake, and Polk counties. On another note, we have GM Cards in stock and will be happy to print more. Call you Region Specialist for a renewed supply.

Metro counties actually showed a decrease in sites to 68, down from 86 . One bright spot was the discovery of an infested cotoneaster shrub in the Apple Valley spray area from 1996. The shrub produced an astounding nine egg masses and six pupae. Wow, that's a "spot" fire. The other "hot spot" this year was over in Eden Prairie where some "uncertified" blue spruce from (you guessed it) Michigan were planted. These did not come through legitimate nursery channels. The USDA is investigating. There are now two known infestations so it seems reasonable to assume at this point that Minnesota skies will hear the sounds of helicopters in the spring.

Officially, "the front" is still back in Wisconsin, but we can clearly hear the thunder to the east. What was that? A few drops of rain? Now, where did I put my umbrella?

The attached maps and listings summarize the catch in Minnesota and neighboring states of Wisconsin and Iowa. We'll know more about gypsy moth in these states following the Tri-State GM Meeting in November so please stay tuned.

Minnesota Gypsy Moth Trapping Program, 1997
AgencyNumber of traps
Minnesota Dept. of Agriculture 8,446
Minnesota Dept. of Natural Resources 700
USDA Forest Service ( federal lands) 250
County Agricultural Inspectors 200
Hennepin County Parks 109
City of Duluth 20
Total 12,965

Gypsy Moth Catch Summary by County, 1997
CountyMoths/ Sites
Aitkin 1 / 1
Anoka 10 / 6
Beltrami 1 / 1
Carver 3 / 3
Dakota 44 / 11
Dodge 2 / 2
Faribault 1 / 1
Fillmore 15 / 14
Freeborn 2 / 2
Goodhue 4 / 4
Hennepin 65 / 28
Houston 23 / 13
Itasca 6 / 1
Lake 1 / 1
Mower 2 / 2
Nicollet 1 / 1
Olmsted 8 / 7
Polk 1 / 1
Ramsey 16 / 10
Sherburne 1 / 1
Steele 1 / 1
Wabasha 9 / 9
Waseca 2 / 2
Washington 15 / 10
Winona 27 / 22
Total 261 / 154